The present invention relates to a side airbag apparatus structured such as to inflate and deploy an airbag between a body side portion and a vehicular seat in the case that an impact is applied to a vehicle from a side, and reduce the impact by the airbag so as to protect an occupant.
For example, as disclosed in Japanese Laid-Open Patent Publication No. 10-81187, a side airbag apparatus has been widely known as an apparatus protecting an occupant from an impact applied to the vehicle from a side due to a side collision or the like. The side airbag apparatus is provided with an inflator and an airbag. The airbag is stored in a seat back (a backrest) of the vehicular seat in a state of being folded so as to be made compact.
In the side airbag apparatus, if an impact is applied to the body side portion of the vehicle from a side, a gas is jetted out from the inflator, and is fed into the airbag. The airbag is inflated and deployed by the gas, and the seat back is broken at a particular portion. The airbag shoots out of the broken position of the seat back in a state of leaving a part of the airbag within the seat back. The airbag is inflated and deployed forward from the seat back in a space between the occupant seated on the vehicular seat and the body side portion. The inflated and deployed airbag is interposed between the occupant and the body side portion making an intrusion into a passenger compartment so as to restrain the occupant. Accordingly, the impact transmitted to the occupant from the side through the body side portion is reduced.
The side airbag apparatus, as described above, inflates the airbag in the space between the occupant seated on the vehicular seat and the body side portion so as to absorb an impact. This space is narrower than a space at a time of other types of collisions than a side collision, for example, a front collision. Further, this space is varied in accordance with a size of the vehicle, and generally, the smaller the size of the vehicle, the narrower the space becomes. Even in such a narrow space, it is important to reliably inflate and deploy the airbag so as to reliably protect the occupant.